Oil-filled bushing



July l, 1930.

G. E. JANssoN 1,769,262

OIL FILLED BUSHING Filed June 30, 1926 Patented July 1, 1930 GUEI'AV E. IANSSON, 0F 'WOLLASTON, MASSACHUSETTS, ASSIGNOB T0 (JOIwl'IDIl.ELEC-V 1 'TBICAL MANUFACTURING CORPORATION, 0l' SOUTB- BOSTON,

OOBPOBATION E MASSACHUSETTS MASSACHUSETTS, A

01m-FILLED Bosma Application led Inno 80,1923. Serial No. 119,724.

This invention relates to'electric insula-v tors and' more articularly to those of the bushing type w ich have lnsulatin enclos-l ing casings comprising a number o tubular sections and which are adapted to contain a. body of insulating fluid or compound, such as o1 Considerable diculty is encountered in this type of bushing in making an oil tight connection between the sections of the outer insulatin casing. Inmy copendin applications, erial No. 119,723, tiled une 30, 1926, and Serial No. 110,126, filed May 19, 1926, respectively, I have shown two diiferent methods of connecting insulator sections of this type and some of the features of the insulator embodying the present invention are disclosed therein.

It is an object of thisvinvention to provide an oil-filled insulating bushing having an outer enclosing casing comprising two or more insulatin tubes ]oined toget er in a permanent` fluid-tight manner at their proximate ends. l It is a further object of theinvention to provide a Huid-tight insulating bushing havmg a twov piece outer shell which will be cheaper to manufacture and more` reliable than the resent bushings of this type.

A urt er object is enerally to improve oil-filled bushing t e insulators.

Fig. 1 shows an e evation artly in section of an insulator embodying t e invention.

Fig. 2 is an enlarged sectional detail of the'` uid tight seal` rovided between the upper and lower insu ating sections of the insulator. l

Fig. 3 is a sectional view of the insulator taken on lines 3-3 of F' 1.

embodying the invention comprises the upper insulating section 10 prov1ded with t usual capes, or petticoats l12, the lower` insulating section 14 provided with external corru tions 16 vat the'lower end thereof, and t e intermediate metal attaching collar or sleeve 18 which surrounds the roximate ends of said sections 10 and 14. e u per insulating section comprises essentia a 5 porcelain tube having preferably stralght As here shown, the linsulating bushing side walls and o en at the top and bottom. The lower insu ating section comprises -a porcelain tube open at thetop and ta ered at its lower end to provide a restricte pasl sa e at the bottom.

heftop of the insulator is provided with an oil reservoir consisting of a metal cylinder 20 which is secured in fluid tight relation to the open top of the insulating section 10. The oil reservoir is rovided with a cap 24 which is screwthreaded to the upper end of said cylinder 20 and forms a cover for the reservoir. A lass cylinder 26 is disposed within said cy inder 20 and the oil level in the insulator and in the glass cylinder 20 is visible at all times through suitable a ertures 28 of the metal cylinder 20. aid reservoir cover 24 is rovided ,with an axial opening through -which a conducting stud 32 is adapted to pass `freely and said opening is covered against entrance of water by a cover 34 which is screw-threaded on said conductor and whichhas a depending apron 36 surrounding said opening.

The lower insulating section 14 is provided with arestricted passage in its lower end in which a bushing 38 Vis secured' by means of albody of cement `40. Said conducting stud 32 is adapted to `be screwthreaded throu l1 and extend beyond said bushing and a ock nut41 is screwed onto the lower extended end of said conductor to prevent rotation of the stud in the bushing. A pacln'ng 42 disposed between the nut and the lower end of'the insulating section.14 serves to provide an oil tight seal thereat.

Said metal collar 18 is adapted to provide a mechanical connection between the upper and lower insulating lsections and. also to provide the support for the insulator. To thisA end said collar is provided `with an integral outstanding flange 44 b which the bushing is ada ted to'be secure to the casing 45 of any esirable electrical apparatus. The `diameter of the collar is adapted to be somewhat larger than that of the lnsulating sections to provide -an annular space therebetween to receive a body of cement 46 by means of which sai'd upper and lower insu'- lating sections are rigidly and permanently fixed within said collar 18. Annular grooves 48 are provided on the inner surface of said sleeve into which the cement is adapted to enter, and those surfaces of the insulating tubes surrounded by the collar may be roughened, thus enhancing the strength of the bond between the sleeve and the insulating sections.

Cement, where it is used in oil filled bushings, cannot always be relied upon to maintam a fluid-tight joint because of its inherent porous structure. Consequently, means is provided to prevent the oil within the insulator from seeping through the cemented joint between the insulating sections 10 and 14. Said means comprises an annular packing washer 50 of some suitable yielding material, as cork, disposed between the proximate ends of said insulating sections.

It is not necessary to provide a breakable joint intermediate the ends of the insulators since the open top construction permits the assembly of the inner parts of the bushing through the top as is set forth in my copending application Serial No. 110,126, filed May 19, 1926. Consequently the joint between the insulating sections l0 and 14 is intended to provide a permanent unitary structure for the enclosing casing of the bushing.

In assembling the outer casing, the packing washer 50 is thoroughly coated with an insulating and oil-insoluble resin or gum, such as shellac, which will enter into the pores of the packing and adhere to the unglazed surfaces at the ends of the porcelain insulating sections 10 and 14. The packing is then compressed by applying a substantial pressure at the outer ends of the two insulating sections while one or more coats 52 of shellac is applied to the outer circumference of the packing and in the' immediate vicinity of the joint. When the shellac has hardened and while the packing is still held in compressed relation between the insulating sections, the cement 46 is put in place between the sleeve 18 and the porcelain sections and allowed to set so that when the cement has set the packing 50 is held in a permanent state of compression thereby between said insulating sections.

The insulator shown herein for purposes of illustrating the invention is made up of two porcelain sections although it is obviousthat any number of sections could be secured together to provide a fluid-tight tube of any desired length.

rlhe construction may be modified in a great many ways without departing from the scope of the invention.

I claim:

1. An oil filled insulating bushing having an outer enclosing casing including two axially disposed insulating tubes and means permanently connecting said tubes together m an oil tight manner including a metal sleeve surrounding said tubes at their proximate ends and spaced therefrom, a body of cement disposed within the space between said sleeve and said tubes, and a packing of compressible material disposed between and held` in compression by the proximate ends of said tubes and the cement, and components including a conductor disposed within said joined insulating tubes, said bushing having an entrancethereto through the end of one of said tubes which is at least as large as the largest diameter of said components, so that said components can be withdrawn through said entrance without breaking the oil-tight connection between the tubes.

2. An oil filled insulator having two axially aligned insulating members, a sleeve disposed around the proximate ends of said members and spaced therefrom, a body of cement contained in the space between said sleeve and said members to bind said sleeve and members together, and compressible packing means disposed between the roximate ends of said members and hel in a compressed state by said insulating members and cement, and an oil proof sealing coating applied to the proximate ends of said insulating members and overlying said packing means.

3. An oil filled insulator having two adjacent insulating members, a collar disposed around the proximate ends of said members and spaced therefrom, a compressible packing disposed between the proximate ends of said insulating members and held in compression by said members, and a body of cement contained in the space between said members and collar and holding said insulating members and said packing in compressed condition.

4. The method of making an oil-tight joint between two porcelain sections having contiguous ends which consists of placing a compressible packing between the proximate ends of said sections, applying a coat of oilroof sealing material to the outside of sai sections in the vicinity and over the outer edge of said packing and binding said seetionsrigidly together by a mass of ce ment which surrounds both sections and the joint therebetweenfand is adherent to said sections and a metal collar which surrounds the sections at the joint between them. i'

5. The method of forming an oil tight joint between two porcelain sections afan' insulator which conslsts of provlding a compressible packing between the contiguous faces of the sections, applying a pressure on said sections to compress said packing, coat` ing the outer surface of the insulator in the vicinity of said joint with an insulating and ios oil-impermeable sealing substance, cementing a connecting sleeve to the outside of said insulating sections in the vicinity of said joint, and holding the packing in compres.

5 sion until the cement hardens.

6. An oil-filled insulator including two axially aligned insulating members spaced apart by a compressible acking washer, an

j attaching collar disposed) about the proxim mate ends of said members and spaced f therefrom, and a bod of cement adapted to occupy said space an fix said members permanently to said collar with said packing washer in a compressed condition therebetween.

7. An insulator comprising two ali ed insulatin tubes, a compressible pac ng washer dlsposed between the contiguous ends thereof and held in compression by said my tubes, and an external connectingsleeve cemented to said tubes intermediate the ends of said insulator and arranged to hold said tubes permanently in pressure engaging relation with said washer.

8. An oil filled insulating bushing including an outer. enclosing casing comprising two axially aligned insulatin shel s, an means comprising a nonbreaka le joint permanently connecting said shells together in an oil-tight manner including a metal sleeve surrounding and spacedfrom said shells at their proximate ends, a packing of compressible material dis osed between and held 1n compression by t e proximate ends of said shells, and means to hold said shells and said compressible packing in the aforesaid relation comprising a. body of cement. disposed within the space between said sleeve and said shells.

In testimony whereof, I have signed my name to th1s specification.

GUSTAV E. JANSSON. 

